Scala: Run & Startup with SBT + Intellij IDEA 12

ArrayFilter.scala

package scala.euler

/*
 * Task: http://projecteuler.net/problem=1
 * Description: Find the sum of all the multiples of 3 or 5 below 1000.
 */

class ArrayFilter(n: Int) {
  val preparedArray = Array.range(1, n)

  // Public
  def sum : Int = {
    return this.filterArray.sum
  }

  private def filterArray : Array[Int] = {
    return this.preparedArray.filter(x => (x % 3 == 0 || x %  5 == 0))
  }
}

ArrayFilterTest.scala

package scala.euler

import org.scalatest.FunSpec
import org.scalatest.BeforeAndAfter

class ArrayFilterTest extends FunSpec with BeforeAndAfter {
  var arrFilter: ArrayFilter = _

  describe("ArrayFilter") {
    before {
      arrFilter = new ArrayFilter(10)
    }

    it("should create an array") {
      assert(arrFilter.preparedArray === Array.range(1,10))
    }

    it("should return sum of filtered elements") {
      assert(arrFilter.sum === 23)
    }
  }

  describe("Euler task") {
    it("should return correct value") {
      arrFilter = new ArrayFilter(1000)

      assert(arrFilter.sum === 233168)
    }
  }
}

build.sbt

name := "Project Euler"

version := "0.1"

scalaVersion := "2.10.0"

libraryDependencies += "org.scalatest" % "scalatest_2.10" % "1.9.1" % "test"

Main.scala

package scala.euler

object Main {
  def main(args: Array[String]) {
  }
}

plugins.sbt

resolvers += "Sonatype snapshots" at "http://oss.sonatype.org/content/repositories/snapshots/"

addSbtPlugin("com.github.mpeltonen" % "sbt-idea" % "1.3.0-SNAPSHOT")